PLA vs PETG vs ABS (and ASA):
which filament for which job

Choosing between PLA, PETG and ABS comes down to three trade-offs. PLA is the easiest to print and the stiffest of the three, but it starts to soften at about 55-60 °C, so a car parked in the sun will deform it. PETG gives up a little stiffness for toughness, holds its shape to roughly 70-80 °C and prints on an open machine, which makes it the practical all-rounder. ABS, and its weather-resistant relative ASA, cope best with heat at around 90-100 °C, but both shrink as they cool and need an enclosed printer and good ventilation.

The numbers on this page come from manufacturer technical data sheets (mainly Prusament and Polymaker), the Prusa Knowledge Base, peer-reviewed studies and textbook polymer values. Datasheet figures for printed test bars depend on print settings, orientation and the brand's own formulation, so treat them as typical values. Where two sources disagree, both are given as a range. For the wider family of filaments, including nylon, PC and composites, see the full chart of 3D printing filament types.

What PLA, PETG and ABS are made of

The three filaments belong to different polymer families, and most of their behaviour on the printer and in use follows from the chemistry. PLA and PETG are both polyesters. ABS is a styrene-based terpolymer with a rubber phase dispersed through it.

PLA: polylactic acid

PLA is a polyester built from lactic acid. The lactic acid is made by fermenting plant starch or sugar from crops such as corn, cassava, sugarcane or sugar beet pulp, and the main industrial route to the polymer is ring-opening polymerisation of lactide (the cyclic dimer of lactic acid) with a metal catalyst, usually tin octoate. Its glass transition temperature is around 60-65 °C and it melts somewhere between 130 and 180 °C depending on grade. PLA is also a packaging polymer: of the PLA produced in 2022, about 35 % went into flexible packaging and 30 % into rigid packaging, which is why it turns up in our coverage of nanotechnology in food packaging.

PETG: glycol-modified PET

PETG is polyethylene terephthalate, the bottle polymer, with part of its ethylene glycol replaced by cyclohexanedimethanol (CHDM). The CHDM unit has six more carbon atoms than the ethylene glycol it replaces, so it does not pack neatly against neighbouring chains. That disrupts crystallisation and lowers the melting temperature, and the result is a clear, amorphous copolyester that extrudes easily into filament. Polymaker lists a glass transition of 81 °C for its PolyLite PETG and Prusa's annealing article gives 75 °C, both within the 67-81 °C range usually quoted for PET itself.

ABS: acrylonitrile butadiene styrene

ABS is a terpolymer of three monomers whose proportions vary by grade: typically 15-35 % acrylonitrile, 5-30 % butadiene and 40-60 % styrene. The styrene and acrylonitrile form a rigid matrix, and the butadiene forms rubbery particles that absorb impact energy. Its impact resistance holds up well at low temperatures, and LEGO bricks have been moulded from ABS since 1963. The glass transition sits at about 105 °C. ABS dissolves in ketones such as acetone, which is the basis of vapour smoothing.

ASA (acrylonitrile styrene acrylate) keeps the same rigid styrene-acrylonitrile matrix and swaps the butadiene rubber for an acrylate rubber. The acrylate rubber has no carbon-carbon double bonds for sunlight and oxygen to attack, and that gives ASA about ten times the weathering and UV resistance of ABS. Its glass transition is slightly lower, around 100 °C against 105 °C for ABS. Prusa describes ASA as a successor to ABS, and it appears through this page as the outdoor answer.

PLA vs PETG vs ABS comparison table

The table sets the four materials side by side. Ranges combine at least two manufacturers; a single figure names its source. Mechanical values are from 3D printed specimens tested in the XY (flat) orientation unless noted.

PLA leads on tensile strength and stiffness and trails on everything to do with heat and sunlight. ABS has the lowest tensile strength on paper and the best elongation and notched impact figures, because it stretches and absorbs energy where PLA cracks. Which one counts as "stronger" depends on how the part is loaded.

PLA vs PETG strength: stiff versus tough

On a tensile test PLA is the strongest of the three. Prusament PLA reaches 51 MPa in printed bars and Polymaker PolyLite PLA 52.3 MPa, against 47 and 50.8 MPa for the same brands' PETG and 33.4 MPa for Polymaker's ABS. PLA is also the stiffest: its modulus runs from 2.3 GPa (Prusament) to 3.4 GPa (Polymaker), while Prusament PETG measures 1.5 GPa.

Stiffness and tensile strength describe how a part behaves before it yields. They say little about what happens when it is bent past that point or dropped. PLA stretches very little before it breaks: Polymaker measures 6.3 % elongation at break in the flat orientation and only 1.8 % across the layers, and textbook values for the bulk polymer are under 10 %. A PLA clip that is flexed too far snaps cleanly.

PETG yields and bends first. Prusament's unnotched Charpy bars in PETG did not break at all, where PLA bars broke at 13 kJ/m². Prusa's own materials guide puts it plainly: PETG's tenacity and flexibility often prevent it from breaking. For clips, brackets, cable guides and anything that gets knocked about, that matters more than the few megapascals PLA has in hand.

ABS is the most ductile in these data sets. Polymaker's ABS stretches 17.9 % before it breaks in the flat orientation and records a notched Charpy impact strength of 18 kJ/m², against 3.3 kJ/m² for its PLA and 2.6 kJ/m² for its PETG. The butadiene rubber particles are what absorb the energy, and ABS keeps that toughness at low temperatures. Prusament's notched test puts its PETG at 6 kJ/m², so the notched and unnotched results rank PETG differently depending on brand and test. A single impact figure is a weak basis for ranking these filaments.

Layer adhesion is usually the real limit

Printed parts tend to fail between layers. Across the layers (the Z direction) Polymaker's PLA falls to 40.5 MPa, its PETG to 42.8 MPa and its ABS to 29.7 MPa, and elongation drops to 1.8 %, 3.3 % and 3.1 % respectively. Prusa Polymers measures interlayer adhesion directly: 17 MPa for PLA, 18 MPa for PETG and 11 MPa for ASA. In these data the drop from flat to vertical is often as large as the gap between the materials, so orienting a part so the load runs along the layers matters as much as the choice of filament. If a part needs to be stiffer than any of them, fibre-filled grades such as CF-PETG are the next step; our page on carbon fibre and graphene filaments covers what the fibres change and what they cost in toughness.

Heat resistance: which one survives a hot car

Heat resistance is where the three separate most clearly, and it follows the glass transition temperature. Below Tg an amorphous plastic is glassy and rigid; around Tg it softens and starts to deform under its own weight or any load. PLA's Tg is 60-65 °C, PETG's 75-81 °C and ABS's 101-105 °C.

Heat deflection temperature (HDT) is the more practical number. It is measured to ISO 75 as the temperature at which a standard bar bends a set amount under a fixed load, and the gap between the materials is similar. At 0.45 MPa Prusament PLA deflects at 55 °C and Polymaker PLA at 60 °C. PETG comes in at 68 °C (Prusament) and 78 °C (Polymaker). Polymaker ABS reaches 100 °C and Prusament ASA 93 °C. Prusa's guide says PLA softens and deforms above 60 °C, PETG suits most exterior use below 80 °C, and ASA shows no deformation up to temperatures near 93 °C.

A car parked in summer sun is the usual test case for these numbers. A 1990 study by the Florida Solar Energy Center at Cape Canaveral found interior air temperatures in unshaded parked cars commonly reaching 150 °F (about 65 °C), with dashboard surfaces rising to nearly 200 °F (about 93 °C). PLA fails that test even in the cabin air. PETG would sit above its HDT on a sunlit dashboard. ABS and ASA are the only ones of the three with HDT values in the range of those peak dashboard temperatures, and even they have little margin on the hottest days.

Softening is only one form of heat damage. Plastics also creep, deforming slowly under a constant load, and creep speeds up as temperature rises. In a 2022 study in the Journal of Mechanical Engineering (Strojniški vestnik), Dogan tested printed PLA, ABS, nylon, PC and two other polymers at 25, 40 and 60 °C under 10 and 20 MPa. PLA had the worst creep resistance of the group and broke at 60 °C even under the lower load. The author's recommendation was to use PLA parts at room temperature with no load or very low static loads.

Annealing PLA, and what it costs in accuracy

Annealing means reheating a finished print above its glass transition and holding it there so the polymer chains can rearrange and part of the material crystallises. For PLA it raises heat resistance considerably. Prusa's annealing tests found PLA gave its best tensile results and a large rise in heat deflection after annealing at 90 °C and above. PETG benefited most at 110 °C, especially in impact tests. ABS did not respond usefully, and Prusa judged it unsuitable for annealing.

The cost is dimensional accuracy. In Prusa's tests every sample shrank most along the X axis while the Z dimension grew slightly, and PLA warped badly at temperatures above 70 °C. A 2023 study in Materials by Stojković and colleagues annealed PLA tensile bars at 60-100 °C for 30-90 minutes. The best tensile gain was modest, 6.28 % (from 30.07 to 31.96 MPa), while the bars changed length by 3.55 mm on average and up to 5.8 mm, far more than their thickness changed. Smaller layer heights combined with higher temperatures produced the largest changes.

Prusa's advice for parts that must fit is to anneal a first batch, measure how much it shrank and then print a second batch scaled up to compensate. Annealing suits brackets and holders where a millimetre does not matter. For close-fitting assemblies, PETG, ABS or ASA printed to size is less work. PLA can go much further in heat with chemistry: grades sold as heat-resistant PLA withstand about 110 °C, and blending the two mirror-image forms of the polymer (PLLA and PDLA) can lift heat deflection from about 60 °C to as high as 190 °C.

PETG vs ABS for outdoor use

ASA is the best of these materials for parts that live outdoors. PETG and ABS each fall short for a different reason, PETG on UV and ABS on UV-driven embrittlement, and PLA does worst of all because it combines UV damage with a low softening point and poor creep resistance.

PLA outdoors: heat, UV and creep

Prusa states that PLA degrades under UV light and is not suitable for outdoor use. UV is only part of the problem. A PLA part in direct sun can approach its 55-60 °C deflection temperature, and any part carrying a steady load, such as a hose hook or a plant pot bracket, will creep. The Dogan creep study showed PLA losing creep strength faster than ABS as both temperature and load increased.

PETG outdoors: heat is fine, UV less so

PETG copes with outdoor temperatures in most climates, and Prusa rates it for most exterior use below 80 °C. It also absorbs little water: Prusament measured 0.10 % uptake after seven days, lower than its PLA or ASA. Its weakness is UV. In a 2021 study in Polymers, Amza and colleagues exposed printed PETG and PLA to three accelerated weathering cycles, 24 hours of UV-B in total with condensation phases at 50 °C. The PETG lost 36 % of its tensile strength (from 31.3 to 20.0 MPa), its elongation at break fell from 3.06 % to 1.36 %, and it turned yellow. The PLA lost 5.3 %.

That result needs care. The PETG was a natural, transparent filament and the PLA an opaque blue, so colour may account for part of the gap, and 24 hours in a UV chamber is a short test. It does show that plain PETG is not UV-stabilised by default, and that clear or light-coloured PETG parts in full sun will change over time.

ABS outdoors: yellowing and embrittlement

ABS has the heat resistance for outdoor use and lacks the UV resistance. Sunlight drives photo-oxidation of the butadiene rubber phase, which breaks polymer chains, turns the surface yellow and makes the part brittle. Prusa's guide notes that outdoor ABS parts turn yellowish and more brittle over time, and lists the lack of UV resistance as the main difference from ASA.

ASA vs ABS

ASA prints much like ABS and was designed for weathering. Replacing the butadiene with an acrylate rubber removes the double bonds that UV attacks, which is why it is used for building siding, exterior vehicle parts and outdoor furniture, and why it retains gloss, colour and mechanical properties outdoors. Prusament says its ASA keeps its toughness and does not turn yellow in outdoor use. Prusa's comparison lists three advantages over ABS: better UV resistance, less warping and less smell. ASA still needs a hot bed (Prusament specifies 110 °C) and an enclosure for larger prints, and it can be acetone smoothed and solvent glued the same way as ABS.

Printing difficulty: stringing, warping and enclosures

PLA is the easiest filament to print well. It runs at about 190-230 °C with a bed at room temperature up to 60 °C, tolerates full part cooling (Prusament specifies 100 % fan) and rarely needs a brim. Prusa Polymers rates its PLA for print speeds up to 200 mm/s. Its main nuisance is some stringing and oozing, which retraction settings usually fix.

PETG is the one that strings. Prusa's guide lists stringing among its drawbacks and notes that bridges and overhangs usually come out worse than in PLA, partly because PETG prints with less fan (50 % in Prusament's settings). It sticks to beds very well, too well on smooth PEI: Prusa warns that adhesion to a smooth PEI sheet may be too strong and recommends powder-coated sheets, while Prusament's data sheet allows smooth PEI with a glue stick as a release layer. PETG runs hotter than PLA, typically 230-260 °C at the nozzle and 70-90 °C on the bed, but it does not need an enclosure. Polymaker recommends drying it at 65 °C for six hours if it has picked up moisture.

ABS is the hardest of the three because it shrinks as it cools. Prusa gives a shrinkage of about 1-2 %, enough to pull corners off the bed and split tall parts between layers when one side cools faster than the other. The fix is a warm environment: a bed at 90-110 °C, a glue stick on PEI, and the printer inside an enclosure so the air around the part stays warm. Both Prusa and Polymaker treat the enclosure as necessary for ABS. ASA behaves similarly with slightly less warping, and Prusament suggests a brim of 3 mm or taller for larger objects.

Fumes are the other reason ABS and ASA need more planning. In a 2016 chamber study in Environmental Science & Technology, Azimi and colleagues measured five desktop printers with up to nine filaments. Styrene from ABS and HIPS was among the VOCs emitted in the largest amounts, at roughly 10 to 110 µg per minute, and ultrafine particle emissions ranged from about 100 million to 100 billion particles per minute, depending mostly on the filament. A 2025 study in Toxics by Gao and colleagues found PLA's VOC emissions relatively low compared with ABS, whose styrene emissions ranged from 0.3 to 113 µg per minute, and recommended good ventilation and local exhaust near printers. An enclosure helps ABS print, and it only protects the room if it is vented or filtered.

Food contact and safety

None of these filaments turns a printed object into safe foodware on its own. Prusa's guide says PLA as a material is food-safe, yet it does not recommend PLA for food contact, because the grooves between layers give bacteria somewhere to grow and are hard to clean. It says the same of PETG: the polymer may be considered food-safe, but Prusa does not recommend it, or any other filament, for printing dishes. For containers it suggests a food-safe epoxy coating and, for PETG, a stainless-steel nozzle.

A "food-safe" statement on a spool describes the raw resin. The part that touches food is a layered print that has passed through a hot nozzle and picked up whatever colourant the spool contains. ABS and ASA both contain styrene, and Prusa flags their fumes as a potential health risk during printing, so they are the least natural fit for kitchen use. The layer-line problem Prusa describes applies to every filament on this page.

Is PLA biodegradable? Composting claims explained

PLA biodegrades under industrial composting conditions and very slowly anywhere else. At 58 °C in an industrial composter, about half of a PLA sample breaks down into water and carbon dioxide in 60 days, and the rest degrades more slowly. Complete biodegradation needs those thermophilic conditions. Prusa's guide warns that ordinary composting will not decompose PLA and that PLA in a garden compost heap ends up as microplastic contamination.

Compostability claims are defined by two standards. The European standard EN 13432 requires that after 12 weeks of composting no more than 10 % of the material remains as fragments larger than 2 mm, that at least 90 % of it biodegrades (measured as carbon dioxide released, relative to a reference material) within six months, and that the resulting compost shows no ecotoxic effects. The American standard ASTM D6400, in its 2021 edition, is titled a specification for labelling plastics designed to be aerobically composted in municipal or industrial facilities, and it covers facilities where thermophilic conditions are reached. Neither standard describes a home compost bin.

So "biodegradable PLA" on a filament box means compostable in an industrial plant, where one accepts it. The standards test a specific material or product, so check which product a certificate covers before relying on it for printed parts with pigments or additives. PETG, ABS and ASA are not biodegradable in either setting. The same compostability questions apply to PLA films and trays, which our pages on nanotechnology in food packaging and active vs intelligent packaging discuss from the packaging side.

Where TPU fits

TPU (thermoplastic polyurethane) is the flexible option and does a different job from the three rigid filaments here. It is rated on the Shore A hardness scale, typically 60A to 90A for printing grades, and stretches enormously: Polymaker's PolyFlex TPU95 reaches about 550 % elongation at break. Prusa recommends 230-245 °C at the nozzle, 60-75 °C on the bed and slow printing, usually around 20 mm/s and no more than 30-40 mm/s, because softer grades buckle in the extruder. It absorbs moisture and should be kept dry. It suits washers, stamps, RC tyres, shoe soles and belts, and the filament types hub compares it with the other flexibles.

Which to choose: PLA, PETG, ABS or ASA for common jobs

Most choices come down to three questions: how hot will the part get, will it see sunlight, and does it need to bend without breaking. The list below applies the data above to typical jobs.

• Display models, figurines, prototypes and fit checks kept indoors: PLA. It prints fastest and most accurately, and its stiffness helps thin walls hold their shape.
• Functional indoor parts such as clips, brackets, tool holders and electronics cases: PETG. It flexes before it breaks and tolerates warmth up to roughly 70-80 °C.
• Parts that carry a constant load, like shelf supports or wall hooks: PETG or ABS. PLA creeps under steady load, and the creep gets worse as the room warms up.
• Parts inside a car: ASA or ABS. Dashboards in direct sun can reach about 93 °C, above the deflection temperature of both PLA and PETG.
• Parts that live outdoors in sunlight: ASA. ABS yellows and turns brittle, and plain PETG lost strength quickly in accelerated UV testing.
• Parts to be smoothed to a glossy finish or solvent-welded: ABS or ASA, both of which respond to acetone.
• Printing in a classroom, office or shared living space without an enclosure: PLA, or PETG with ventilation. Keep ABS and ASA for a vented, enclosed printer.
• Parts that must be stiffer than any of these: a fibre-filled grade, covered on the carbon fibre filament page.
• Cups, plates and food storage: none of them without a food-safe coating, for the layer-line reasons Prusa gives.

For a first printer and a first spool, PLA is the least frustrating way to learn, since it needs no enclosure, no hot bed and little tuning. PETG is the natural second material for parts that take knocks or sit somewhere warm. ASA makes sense once there is an enclosed, ventilated printer and a part that has to survive the weather. The nanopack.org home page links the filament pages with the packaging side of the site, where PLA appears again as a film and tray polymer.